1. Field of the Invention
The invention relates to strain gauges, specifically to a device that generates effects, such as sounds or lights, in response to strain, such as caused by body position or movement.
2. Description of Prior Art
Toys
Toys with good play value allow variation and flexibility in play, as well as providing freedom for imagination and creativity. Interactivity, that is, the ability of a toy to respond to a user""s action by emitting an effect, results in good play value. Sound effects have been used during play activity for many years, the sounds assisting the child to engage in imaginary activity or play. Children commonly act a role in the context of physical activity, and sound is ideally directly linked to this physical activity. Examples of toys with sound effects are crying dolls or pop guns. Lights have also been linked to play activity. Examples are light-sabers, glow-in-the-dark stars or necklaces, and hand held flashlights used to play light tag.
Wearable signal generating toys are especially advantageous and have been discovered to have particularly good play value. The benefits of wearability are that the toy interfaces well with the child""s activity, that is, by adding to and enhancing the activity without any hindrance.
Signal generating wearable toys are known. One example with a sound effect device is described in Martin, U.S. Pat. No. 5,648,753 (1997). This patent is for a toy that can be worn on the arm. It has a transmitter that directs an infrared signal to a receiver that in turn plays a sound effect. In the embodiments described in the Martin patent, to play a sound effect the user must depress trigger switches. This has the disadvantage that it is disruptive for a child to manually push buttons on an object and play at the same time. Such prior art designs do not allow the user to control sound effects while playing with the toy in a more natural, realistic manner. Furthermore, the Martin device has the disadvantage that the sound effect is played to completion once the buttons are pushed, a disadvantage shared with most sound-making toys on the market. It is not possible to stop the sound once it starts, so the effect is not under the user""s control.
Another such device is described in Spraggins, U.S. Pat. No. 4,820,229 (1989). Spraggins describes a wearable effect emitting gauntlet that can be worn on the arm. The effect consists of emitted lights and sounds to simulate lasers and phasors. This device is controlled by mechanical switches. The sounds are not linked to the child""s natural movement during play, but must be activated by the hand not wearing the gauntlet. Furthermore, the sound loudness is not correlated with the degree of movement, nor can the light and sounds emitted reflect the speed of movement. Finally, a drawback of all switch-activated devices is that the area of the control switch is rather small. A distributed switch, i.e., one with a larger active area, would be more desirable.
Yanofsky, WO 9604053 (1996), describes a wearable toy glove that produces sounds stored in memory, with different sounds generated by different switches, pressure contact, or electrical contact. The tone generator includes a CPU which converts values stored in memory into an analog wave-form sent to a speaker to produce the recorded sound. The Yanofsky toy can be worn only on the hands. The glove may be cumbersome to wear, especially for small children. Furthermore, the device is not sensitive to very small movements.
Ferber, U.S. Pat. No. 5,455,749 (1995) describes a wearable article, such as a shirt, onto which current carrying materials have been printed. A battery, a current-operated sound and/or light emitting module, and a control means for controlling the operation of the current operated module can be mounted on the shirt. The emissions are unrelated to body position.
Rawson, U.S. Pat. No. 5,436,444 (1995) describes a sound-generating wearable motion monitor with possible toy applications. The Rawson device is based on a laser, optical fiber, and photo-receiver. The physical movement of this optical fiber generates a signal that is output to an amplifier. This technology is expensive and unlikely to withstand use by children. Furthermore, the device only emits a noise-like signal whose amplitude and average frequency mimic the motion, not noises that would delight children. Finally, the device is difficult to miniaturize so that it can be, for example, worn on a finger.
Reinbold et al., U.S. Pat. No. 6,033,370 (2000) describe an interactive force feedback device with toy applications. The device is a capacitive force sensor comprising a plurality of layers forming a force sensing detector whose output signal responds to pressure. The device is incorporated into objects such as squeeze balls or shoes for sensing applied force. This device is not wearable, nor is it sensitive to delicate movements: it is designed to measure significant forces.
Gastgeb et al., U.S. Pat. No. 4,904,222 (1990) describe toy swords and drumsticks that emit sounds and lights when they are repeatedly waved. The effects are produced by a piezoelectric element incorporated in the body of the toy that gives a transient voltage when flexed/bent. The toy is connected by a cable to the effect emitters, which generate one sound that varies in loudness proportionally with the oscillation of the sword or drumstick and another tone that varies when the frequency of the electrical signal exceeds 300 hertz. The toy is not wearable, but hand-held. It has the disadvantage that piezoelectrics cannot generate a d.c. response, so the signal must be oscillatory. Thus, static positions cannot generate sounds. Furthermore, the effects are produced only by flexing a stiff member, which is disadvantageous for many applications.
It would be further desirable that the effect emitting device could be incorporated into a variety of existing devices to make them more interactive. The effect emitting device thus incorporated should be inexpensive.
Rehabilitation
After an injury, a person may require rehabilitation to help regain the use of a limb. Rehabilitation and training are facilitated by feedback, which may be in the form of sound or light signals, small electric shocks, a temperature change, or touch by an actuator. Feedback is particularly useful if the intensity of the feedback signal is correlated with the magnitude (or other characteristics) of the motion. Such interactive devices allow a person to monitor his or her progress.
Devices that attach to the limb and provide audio feedback are known. A considerable number of biofeedback devices related to rehabilitation have been patented, and often these make use of sounds to provide feedback. However, such biofeedback systems are often immobile and complicated, or they are controlled by computer. Furthermore, many rehabilitation devices deliver a fixed feedback signal when a threshold is exceeded. For these devices, the intensity of the signal does not depend on the characteristics of the motion. Burdea et al., in U.S. Pat. No. 5,429,140 (1995), describe a rehabilitation system that employs a force feedback system, such as a force feedback glove, to simulate virtual deformable objects. This system is complex and comprises numerous components. Furthermore, this system is costly. Finally, this system is not readily wearable or portable.
Dempsey, U.S. Pat. No. 4,557,275 (1985) teaches a biofeedback system for rehabilitation therapy. The system includes a plurality of mercury switches arranged to respond to change in position of a body member. Circuitry responds to the closing of the switches to give distinct signals. The signal processing circuitry is housed within a console. Audible signals are delivered by headphones, and visible signals are provided by colored lamps. The Dempsey switches are complex and bulky, and the mercury poses a potential health hazard. The system does not provide feedback based on the extent of movement, but rather whether the movement has crossed some threshold that causes a switch to close.
Stasiuk, CA 2184957 (laid open 1998) describes a rehabilitation device that generates audio feedback indicative of a load applied by a limb (not the position or movement of a limb). A load sensor is attached to the limb, and the load signal is compared to a threshold signal. The feedback signal depends on the difference between the load and threshold signals. The load sensor comprises plates separated by insulators, forming a capacitor. Loading the sensor changes the plate spacing and thus the capacitance. A control unit is worn on a belt, and headphones provide the audio feedback. This is a portable, wearable system. However, it is based on compression rather than stretching, and thus is not adaptable to being worn on body joints, such as finger joints or knees. The control unit is large, approximately 150 mmxc3x9775 mmxc3x9750 mm, and hence cannot be worn on small limbs such as fingers.
Strain Gauges
Strain gauges, i.e., devices that measure change in length, are known and are commercially available. Strain gauges may utilize a change in an electrical property of a material, such as resistance or capacitance, to measure strain Examples of strain gauges based on films of the conjugated polymer polyaniline and on ion-implanted polymers are given in Giedd et al., U.S. Pat. No. 5,505,093 (1996). Strain gauges based on conjugated polymer coated textiles are described below.
Textiles That Sense Stretching
Electrically conductive textiles that change resistance upon stretching (i.e., under strain) and/or exposure to heat are known. De Rossi et al. have shown that polypyrrole coated LYCRA shows a piezoresistive effect (see De Rossi et al., Mater. Sci. Eng. C, 7(1), 31-35 (1998); De Rossi et al., xe2x80x9cDressware: Wearable piezo- and thermoresistive fabrics for ergonomics and rehabilitation,xe2x80x9d presented at the XIX Ann. Intl. Conf. IEEE and EMBS, Chicago, Oct. 30-Nov. 2, 1997; and De Rossi et al. patent IT 1291473 (1997)). De Rossi et al. believe that this piezoresistive effect is due to an increase in the number of contacts between the fibers woven into the fabric when the fabric is stretched. A decrease in resistance of 20% was reported for an increase in length of 1% obtained by stretching. These materials are therefore sensitive strain gauges. Metal coated fabrics were expected by De Rossi et al. to show the same piezoresistive effect. The deposition of metallic films using vacuum deposition was counted among the usable techniques for producing piezoresistive fabrics in the invention by De Rossi et al., patent IT 1291473 (1997). Other methods mentioned for depositing conducting layers on various materials included writing a pattern by ink-jet printing.
De Rossi in his patent IT 1291473 teaches a method and an apparatus for measuring the movement of body segments. The apparatus is a glove comprising sensing areas made of conjugated polymer coated textiles, wiring segments that transfer the signal to a signal processing unit, a personal computer, and software for interpreting the signal.
The De Rossi system is wearable, but not portable. In addition to sensing regions, it comprises textile zones of high conductivity for transferring the sensed signal to a device for signal processing. It is also complex, requiring a computer and software for calibration and interpretation of the signals. Importantly, it does not emit any effects, but instead displays processed results on a computer screen.
A wearable, wireless (no communication with computer necessary) device, consisting of a stretchable responsive material with electrical properties that change upon stretching, a power source, a regulating electrical circuit that generates a signal in response to stretching or relaxing the stretchable material of the device, and an electrically controlled effect emitter that produces an effect, such as a sound, light, or infrared light, in response to the signal from the regulating circuit. The magnitude of the emitted effect can be directly modulated by the degree of bending of a wearer""s body joint (elbow, knee, finger, shoulder, back, etc.) or by extension of a body part (arm, leg, neck, etc.) or by the speed or number of a wearer""s movements. The device can also be incorporated into other objects, such as stuffed toys. The device can be used for a wide variety of purposes, including as a toy, for biofeedback purposes, and as a remote control device.
Objects and Advantages
Accordingly, one object of the present invention is a wearable effect-emitting device. This has the advantage of allowing effects to be produced portably and without hindrance.
Another object is an effect-emitting device that produces effects correlated with body positions or movements. This provides the advantage that the effects are due to the body positions or movements and that no extra motions, such as pushing buttons or switches, are necessary.
Another object is to provide an effect-emitting device for which the magnitude or type of effect depends on the magnitude, speed, or other characteristics (static or dynamic) of the user""s movements. Linking the effect to the activities of the user, rather than a predetermined program, makes the device more interesting and fun. This has the advantage of providing feedback and good play value, as well as making it possible for those with limited motion to use the device.
Another object is to provide an effect-emitting device that can be worn on any bendable or stretchable body segment. This provides the advantage that different effect emitters can be worn on different parts of the body, or the same effect emitter can be placed on different parts of the body. This allows a number of different effects to be produced by the wearer, the sequence of which is controlled by the wearer.
Another object is to provide an effect-emitting device controlled by the deformation of a potentially large area instead of a small switch. This allows additional design options as well as increased ease of use and/or enjoyment of the articles.
Another object of the present invention is to provide an effect-emitting device that can be incorporated or designed into other articles such as toys and the like. This allows increased enjoyment of existing articles.
Another object of the present invention is to provide an inexpensive effect-emitting device. This has the advantage of making the device affordable in a variety of price-sensitive markets.
Another object of the present invention is to provide an effect-emitting device that does not rely on a computer. This has the advantage of portability and low cost, and well as freeing the user from a tangle of wires.
Another object of the invention is a robust effect-emitting device. This has the advantage of allowing the device to stand up to rough use, such as by playing children.
Another object of the invention is an effect-emitting device that is sensitive to small movements. This allows the amplification of small differences in position or speed, which is especially useful for rehabilitation or training. It also has the advantage of making use of naturally small movements, such as ear wiggling, to produce effects.
Another object of the invention is to provide an effect-emitting device whose effects can cause delight. This has the advantage of good play value. For rehabilitation or training, it has the advantage of making the use of the device more pleasant.
Another object of the invention is to provide an effect-emitting device that can be miniaturized. This has the advantage of making the devices inexpensive, light-weight, and more wearable on small body parts.